“Avatar” advances the art and technology of visual effects in so many areas — character animation, environments, rendering, performance capture, lighting and more — that winnowing down the bake-off presentation to 15 minutes is a challenge.

“The entire movie is an effect,” says helmer James Cameron, and vfx supervisor Joe Letteri concedes, “You can’t touch every scene, especially in a movie of this size.”

As all experienced bake-off hands know, it’s best to tell a pic’s story in brief during the 15-minute reel. “Even just for myself sitting in the audience watching the reels,” Letteri says, “it’s best if I really understand what I’m seeing in context.”

So Letteri will emphasize the digital Na’vi tribe. “You’ve got this whole planet, all this stuff you need to create, but it still comes down to these characters. If you don’t have characters, you want to watch, you don’t have a movie.”

Cameron started planning “Avatar” after his triumph on “Titanic” and gave Digital Domain, which he’d helped found, two years to develop the technology.

It took more like eight for the tech to mature, however, and by then Cameron and DD had parted ways.

Weta Digital replaced DD to lead the way on “Avatar,” with nine other shops contributing, including ILM “who did some pretty spectacular work,” per Cameron.

“One of the tricks will be to spread the love and make sure all the vendors are well represented,” he adds. “Of course Weta is getting the lion’s share of the glory because they cracked the code of how to get a purity of emotion in CG characters that had never been done before.”